Counterclockwise rotation of the heart; correlation of electrocardiography and chest radiography and their clinical significance.

Electrocardiograms of 3,470 patients, and their 1,430 available radiographs, were reviewed to ascertain the cause of counterclockwise rotation of the QRS complex and of the heart. Seventy-eight patients had the pattern of q in V2, or V3 to V6, and a transitional zone shifted to the right (counterclockwise rotation of the QRS). They all had widening of the aorta, and in the majority the pulmonary artery trunk was not visible by posteroanterior chest radiography. The data suggested that sclerotic lesions of the thoracic aorta are important causes of counterclockwise rotation of the heart and the QRS. Although most patients were in an older age group, cardiac hypertrophy, enlargement, or damage were not found to contribute to the etiology of counterclockwise rotation of the QRS; they may even counteract the development of counterclockwise rotation of either the heart or the QRS axis.